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T. J. PERRIN.

ELECTRICAL SWITCH BOARD] No. 315,331. I Patented Apr. '7. 1885.

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T. J; PERRIN.

ELECTRICAL SWITGEBOARD.

" Patented Apr. 7, 1885.

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THOMAS J.-PERRIN, or BROOKLYN, ASSIGNOR TO CHARLES r. HUNTINGTON,

PATENT OFFICE.

OF NEW YORK, N. Y.

ELECTRICAL SWITCH-BOARD.

SPECIFICATION forming part of Letters Patent No. 315,331, dated April 7, 1885.

' Application filed June 25, 1884. (No model.)

To all whom it may concern.-

Be it known that I, THOMAS J. PERRIN, of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Electrical Switch- Boards, of which the following is a specifica tion.

My invention relates to the construction of switch-boards used in telephone and telegraph exchange systems. The primary object is to provide a novel way whereby the operator or operators may ascertain what lines are in use or connected up.

It also consists in certain details of construction which contribute to make up an efficient switch for telephonic and telegraphic intercommunication. My invention is, however, especially designed for telephone-exchanges, and will be herein described as so applied.

In theaccompanying drawings, Figure 1 is a section of a line-terminal, showing my improvements applied; Fig. 2, an end view of the plug-hole; Fig. 3, a view of the clearingout annunciator and switch; and Fig. 4, a diagram of two of our improved switch-boards, showing the arrangements oflines and circuits.

Where a large number of lines enter a cen-' tral office,it is desirable to divide them up among several operators. In such an arrangement each operator is provided with a board with terminals for all the lines; but he only answers the calls from a given number of lines. V

In Fig. 4 I have shown two boards and sixteen lines. Each line is normally electrically connected with a terminal in each board. Thus line 1 is connected with terminal 1 in board X, and with terminal 1 in board Y, and the other lines are similarly connected.

For illustrating my system I will suppose that the operator at X answers the calls from lines-1 to 8, inclusive, and the operator at Y the calls from 9 to 16, inclusive.

In Figure 1 is shown an enlarged view of one of the line-terminals.

In a suitable frame, A, is arranged an electro-magnet, B, having ahollow metallic spool, a. An inductive rod or core, 12, (preferably of soft iron,) extends through the spool a and the frame A. A contact-spring, O,secured 5o to the rear of the board, normally bears upon a contact-stud, c. The main line is connected with the spring and stud, so that when the circuit is closed the current runs from line D to spring Q to stud c, or vi'ce-versa,thence to line again through the operators telephone and other appliances, as is explained fur: ther on. The lineE includes the eleotro-rnagnet B and a local battery, L B, as illustrated in Fig. 4. The terminals d d of the line E are 6 setinthe face of the board and are normally out of electrical connection, as in Figs. 1 and 2. The main-line connections are shown in Fig. 4, at Nos. land 10. The circuit is from line to spring and stud of No. 1 at board 65.

X, then to spring and stud of No. 1 at board Y, thence through operators telephone F. to earth. The 10s are similarly connected through telephone F of board Y. All the other corresponding numbers on thetwo boards, .7 3

aresimilarly connected. Each correspond: ingly-numbered set of line'tcrminals is shown as provided with a circuit, E, and local bat= tery L B. Taking for illustration the terminals of line No. 1, the local-battery circuit passes from battery through the coil of elec- I bro-magnet in board X to coil of electro-magnet in board Y, thence to the terminals d d in both boards, and to battery again. The circuit from the local battery is normallyopen, 80 i but may be closed by electrically connecting the terminals d d in either board. The plug G is composed of a handle, 6, of non-conductiug material, a central conductingrod, f, ex-

tending entirely through the handle and pro x jecting somewhat at the plug, and a conducting-sleeve, 9, adapted to electrically connect the terminals d d to close the local circuit, but insulated from the rod f. The projecting end of the rod f serves to push in the core b o ture, I, normally held back by a spring, J, a, y,

pivoted latch, K,that engages with thearmaoperators telephone are established, as described below.

The operation of the apparatus is as follows:

Suppose, for instance, that subscriber N o. 1 deires to communicate with subscriber No. 10. He signals the operator through telephone F, and the operator examines the terminal of line No. 10 to see if that lineis in usethat is, he presses a plug against the rod b, and if the plug adheres to the rod, or the rod does not give way to the plug, he infers that the rod is magnetizedt'. e., there is a current traversing the electro-magnet, and consequently there' must be a plug in terminal No. 10in one ofthe other boards, so that the circuit through the terminals d d of the local battery-circuit is completed. If, however, he finds that the line is not in use,he proceeds to call up subscriber N o. 10 by sending a signaling-current over his line. The connection between subscribers Nos. 1 and 10 is then made (as indicated in Fig. 4, board X,) by the plugs M M, that are connected with the clearing-out annunciator, Fig. 3. When the plugs are inserted,they first break the connection between G and c and then close the local circuit through d d. The main circuit is then from line 1 to spring 0, to rod 1), through plugs to rod 1) at No. 10, thence to spring and to line 10.

When the subscribershave finished communicating with each other, one of them sends a current over the line, which energizes the electro-magn'et H and attracts the armature Lthus disengaging the latch K,which falls and makes contact with the stud m, thus establishing a branch circuit through the operators tel ephone, who is informed that he can disconnect their lines.

It will be observed. that while the subscribers are communicating with each other the operator cannot overhear them. It will also be noted that when a terminal has been plugged the main line will be opened at O c at that terminal, and therefore all the correspondinglynumbcred terminals on the boards following the one plugged will be cut out of the line. As the local E is completed, however, the operators at these boards will know from the magnetism of the cores 2; of those terminals, that the line is in use.

I claim as my invention- 1. The combination, substantially as set forth, in a multiple series of switch-boards, of the subscribers lines and their terminals,each of which comprises the separable contacts, the electro-magnet, the sliding core, the circuit of a local battery including the coil of said magnet, and the normally-open terminals of the local circuit.

2. The combination, substantially as set forth, in a multiple switch-board, of a main line, its separable terminal contacts, a testing or indicating electromagnet at each of said separable terminal contacts, a local-battery circuit which includes the coils of all of said magnets, the local-battery terminals at each magnet, and the plug for separating the contacts of the main line and completing the localbattery circuit.

3. The combination, substantially as set forth, in a multiple switch-board, of a main line, its separable terminal contacts on the several boards, a testing or indicating electromagnet at each of said separable terminal contacts, a local-battery circuit which includes the coils of all of said magnets, the local-battery contacts at each magnet, the plug for separating the contacts of the main line and completing the local-battery circuit, and operators instruments, which are normally included in the main line, but are disconnected therefrom by the separation of the main-line contacts.

4:. The combination, substantially as set forth, in a multiple series of switch-boards, of the subscribers lines, a terminal in each board corresponding to each line and electrically connected therewith, a test or indicating magnet at each terminal in each board, a local circuit which includes all the test-magnets of each line, and a circuit-closer which completes said local circuit whenever the line is in use,whereby the operator at any board is apprised of the line being in use by the magnetic condition of the core of said magnet at that board.

In testimony whereof I have hereunto subscribed my name.

THOMAS J. PERRIN. XVitnesses:

E. O. DAVIDSON, NELLIE L. HotMEs.

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